Most legitimate writing communities promote positive, inclusive, and respectful writing. Adult fanfiction, especially when it involves themes like'skinny dip' in an adult and inappropriate way, does not fit into this framework. There are better ways to explore creativity within the boundaries of legality and respect.
The writing community has certain ethical and legal boundaries. Fanfiction should be a form of creative homage that respects the source material and its audience. Adult fanfiction, which may involve explicit or inappropriate content, goes against these principles.